Regex Tester
Test regular expressions against text and inspect matches instantly.
Enter pattern and text
Results
About this tool
Regex Tester lets you test regular expressions against text instantly. It helps developers validate patterns, inspect matches, experiment with flags, and debug search logic for validation, parsing, and text processing tasks. It is designed for quick development tasks such as debugging, formatting, validating, encoding, decoding, and inspecting data.
How to use Regex Tester
- Enter a regular expression pattern in the pattern field.
- Optionally add flags such as g, i, or m.
- Paste your test text into the input box.
- Click Test Regex to see matches and match count instantly.
- Review the results and copy or refine your pattern as needed.
Why use Regex Tester?
Regex Tester helps developers build and debug regular expressions faster. It is useful for text validation, search rules, pattern matching, content extraction, and form input testing during development. This makes it useful when working with APIs, configuration files, logs, databases, web pages, or structured data.
Practical guide
Common use cases
- Test regular expressions against sample text before using them in code, forms, scripts, or automation.
- Check patterns for emails, URLs, numbers, IDs, dates, filenames, log lines, and custom text formats.
- Debug patterns that match too much, too little, or nothing at all.
- Build safer extraction rules before applying them to real data.
Example workflow
Enter a regex pattern, paste representative sample text, review the matches, and adjust the pattern until it captures only the intended values. Test both matching and non-matching examples so you can reduce false positives before using the pattern in production code.
Practical tips
- Test with realistic sample data, but anonymize sensitive values first.
- Escape special characters carefully, especially dots, brackets, slashes, parentheses, plus signs, and question marks.
- Add negative test cases to confirm the pattern does not match unwanted text.
- Regex behavior can differ by programming language or engine, so verify the final pattern in your target environment.
Privacy and data note
Use sample or anonymized text when testing regex patterns. Avoid pasting real customer records, private logs, medical data, financial identifiers, access tokens, or confidential business data into an online regex tester.
Frequently Asked Questions
What does Regex Tester do?
Regex Tester checks how a regular expression pattern matches against your input text and shows the results instantly.
Can I use regex flags like g or i?
Yes. You can enter standard JavaScript regex flags such as g, i, and m.
Does it show all matches?
Yes. If you use the global flag, the tool will list all matches found in the text.
Is Regex Tester free to use?
Yes. You can use this online tool for free.
Do I need to install anything to use this tool?
No. You can use this tool directly in your browser without installing extra software.
Can I use this tool on mobile?
Yes. This tool can be used on desktop, tablet, and mobile browsers.